Genetic Regulation of Cell Division Initiation in Bacillus subtilis

Abstract

The growth and division properties of a temperature-sensitive mutant of Bacillus subtilis defective in the initiation of cell division have been studied. Log-phase cells transferred from 30 to 45 C continue to increase in length but fail to initiate new divisions. Deoxyribonucleic acid synthesis continues at 45 C, and genomes are segregated along the filament length. When filaments are returned to 30 C, division initiation resumes, and the long multinucleate clones are partitioned into normal-size cells. Occasionally, multiple cross walls initiate in close proximity, resulting in tiny cells, some of which are anucleate. Division resumption is sensitive to protein synthesis inhibitors, suggesting there is a new protein required for the initiation of division in filaments. Cell division has been studied in bacteria at the cellular level by several approaches (1, 5,

The Bacillus subtilis division protein DivIC is a highly abundant membrane‐bound protein that localizes to the division site

“…It will be particularly interesting to establish the dependence of DivIC localization on other division proteins, particularly FtsZ and DivIB, and vice versa. Like FtsZ, DivIB and DivIC are involved in the initiation of division (Mendelson and Cole, 1972;Callister and Wake, 1981;Levin and Losick, 1994) and could become localized well before invagination of the membrane starts. Germinated and outgrowing spores, in which the first division is reasonably synchronous, will be used to examine the order and dependence of localization of the division initiation proteins in B. subtilis.…”

“…To establish the validity of the wild-type DivIC identification, an isogenic DivIC mutant strain, SU347, containing the div-355 (ts) mutation was also tested. This strain is defective in initiation of division at 45ЊC, forming long filaments, but can grow and divide normally at 30ЊC (Mendelson and Cole, 1972). Both 168 and SU347 were grown to exponential phase in Penassay broth at 30ЊC, and a portion of each culture was shifted to 45ЊC.…”

“…Several temperature-sensitive mutations in divIB have been identified, and one in particular (ts12 ) causes a defect in initiation of division, resulting in non-septate filaments (Callister and Wake, 1981;Harry et al, 1993). A mutation in divIC, designated div-355, has also been shown to cause a temperature-sensitive defect in initiation of division -the mutant strain forms non-septate filaments when grown at 45ЊC (Mendelson and Cole, 1972). This div-355 phenotype is the result of a 5 bp insertion near the 3Ј end of the gene (Levin and Losick, 1994).…”

Use of Bacillus subtilis minicells to demonstrate an antigenic relationship between the poles and lateral cylindrical regions of rod-shaped cells

“…DISCUSSION Bacterial poles are produced during cell division. In view of the fact that cell growth and division are under separate genetic control, differences in the composition of poles and lateral cylindrical regions have been sought by several investigators (3,5,7). We have taken advantage of the fact that minicells produced by the CU403 div IV-B1 mutant consist essentially of only cell pole surface (8,9).…”

“…Each daughter cell consists of two poles, one of which is a generation older than the other, connected by a cylindrical region. Septum formation, and consequently pole production, is known to be under specific genetic control distinct from that which regulates cell growth by cylindrical length extension (7). It is of interest to determine whether the composition of the cell surface in the cylindrical portions of the cell is identical to that found in the poles.…”